A US judge has slapped a gag order on former president Donald Trump ahead of his trial on charges of trying to overturn his 2020 election loss.

The order prevents Trump from targeting US prosecutors, court staff and potential witnesses involved in the criminal case.

It follows recent outbursts in which Trump lashed out at US District Judge Tanya Chutkan, calling her a “biased, Trump Hating Judge”.

He has also labelled the lead prosecutor Jack Smith “deranged” and a “thug”.

Trump’s lawyers tried to argue that the comments were part of the “rough and tumble” of politics.

But Chutkan asked: “Because he is running for president, he gets to make threats?”

In issuing the gag order, Chutkan said Trump’s language presented “a danger to the administration of justice”.

“His presidential candidacy does not give him carte blanche to vilify public servants who are simply doing their jobs,” she said.

“When you start to use a word like ‘thug’ to describe a prosecutor doing their job, that wouldn’t be allowed by any other criminal defendant,” Chutkan said.

“Just because the defendant is running a political campaign does not allow him to do whatever he wants.”

Chutkan said she would not allow Trump, who has pleaded not guilty, to “launch a pre-trial smear campaign” against people involved in the case.

“No other criminal defendant would be allowed to do so, and I’m to going to allow it in this case,” Chutkan said as she issued the order.

The order bars Trump and lawyers in the case from personally targeting Smith, prosecutors working with him and court staff. It also prevents Trump from discussing potential witnesses as it relates to their testimony at trial.

Smith had sought the order because Trump’s language could “prejudice” participants and have a “chilling” effect on witnesses.

-with AAP